Table Of ContentProceedings of Previous Easter Schools in Agricultural Science, published by Butterworths,
London
*SOIL ZOOLOGY Edited by D. K. McL. Kevan (1955)
THE GROWTH OF LEAVES Edited by F. L. Milthorpe (1956)
*CONTROL OF THE PLANT ENVIRONMENT Edited by J. P. Hudson (1957)
•NUTRITION OF THE LEGUMES Edited by E. G. Hallsworth (1958)
THE MEASUREMENT OF GRASSLAND PRODUCTIVITY Edited by J. D. Ivins
(1959)
•DIGESTIVE PHYSIOLOGY AND NUTRITION OF THE RUMINANT Edited by D.
Lewis (1960)
•NUTRITION OF PIGS AND POULTRY Edited by J. T. Morgan and D. Lewis (1961)
•ANTIBIOTICS IN AGRICULTURE Edited by M. Woodbine (1962)
THE GROWTH OF THE POTATO Edited by J. D. Ivins and F. L. Milthorpe (1963)
•EXPERIMENTAL PEDOLOGY Edited by E. G. Hallsworth and D. V. Crawford (1964)
THE GROWTH OF CEREALS AND GRASSES Edited by F. L. Milthorpe and J. D.
Ivins (1965)
•REPRODUCTION IN THE FEMALE MAMMAL Edited by G. E. Lamming and E. C.
Amoroso (1967)
•GROWTH AND DEVELOPMENT OF MAMMALS Edited by G. A. Lodge and G. E.
Lamming (1968)
•ROOT GROWTH Edited by W. J. Whittington (1968)
•PROTEINS AS HUMAN FOOD Edited by R. A. Lawrie (1970)
•LACTATION Edited by I. R. Falconer (1971)
•PIG PRODUCTION Edited by D. J. A. Cole (1972)
•SEED ECOLOGY Edited by W. Heydecker (1973)
HEAT LOSS FROM ANIMALS AND MAN: ASSESSMENT AND CONTROL Edited
by J. L. Monteith and L. E. Mount (1974)
•MEAT Edited by D. J. A. Cole and R. A. Lawrie (1975)
•PRINCIPLES OF CATTLE PRODUCTION Edited by Henry Swan and W. H. Broster
(1976)
•LIGHT AND PLANT DEVELOPMENT Edited by H. Smith (1976)
PLANT PROTEINS Edited by G. Norton (1977)
ANTIBIOTICS AND ANTIBIOSIS IN AGRICULTURE Edited by M. Woodbine
(1977)
CONTROL OF OVULATION Edited by D. B. Crighton, N. B. Haynes, G. R. Foxcroft
and G. E. Lamming (1978)
POLYSACCHARIDES IN FOOD Edited by J. M. V. Blanshard and J. R. Mitchell
(1979)
SEED PRODUCTION Edited by P. D. Hebblethwaite (1980)
PROTEIN DEPOSITION IN ANIMALS Edited by P. J. Buttery and D. B. Lindsay
(1981)
PHYSIOLOGICAL PROCESSES LIMITING PLANT PRODUCTIVITY Edited by C.
Johnson (1981)
ENVIRONMENTAL ASPECTS OF HOUSING FOR ANIMAL
PRODUCTION Edited by J. A. Clark (1981)
EFFECTS OF GASEOUS AIR POLLUTION IN AGRICULTURE AND
HORTICULTURE Edited by M. H. Unsworth and D. P. Ormrod (1982)
CHEMICAL MANIPULATION OF CROP GROWTH AND DEVELOPMENT Edited
by J. S. McLaren (1982)
CONTROL OF PIG REPRODUCTION Edited by D. J. A. Cole and G. R. Foxcroft
(1982)
SHEEP PRODUCTION Edited by W. Haresign (1983)
UPGRADING WASTE FOR FEEDS AND FOOD Edited by D. A. Ledward, A.J.
Taylor and R. A. Lawrie (1983)
FATS IN ANIMAL NUTRITION Edited by J. Wiseman (1984)
• The titles are now out of print but are available in microfiche editions
Immunological Aspects of
Reproduction in Mammals
D. B. CRIGHTON, MSc, PhD, DSc, FIBiol
University of Nottingham School of Agriculture
BUTTERWORTHS
London Boston Durban Singapore Sydney Toronto Wellington
All rights reserved. No part of this publication may be reproduced or transmitted in any form
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This book is sold subject to the Standard Conditions of Sale of Net Books and may not be
re-sold in the UK below the net price given by the Publishers in their current price list.
First published 1984
© The several contributors named in the list of contents 1984
British Library Cataloguing in Publication Data
Immunological aspects of reproduction in
mammals.
1. Reproduction—Immunological aspects
2. Mammals—Reproduction
I. Crighton, D.B.
599.01'6 QP251
ISBN O-408-10865-7
Library of Congress Cataloging in Publication Data
Main entry under title:
Immunological aspects of reproduction in mammals.
Proceedings of the 38th Nottingham Easter School.
Bibliography: p.
Includes index.
1. Reproduction—Immunological aspects—Congresses.
2. Mammals—Physiology—Congresses. I. Crighton, D. Β.
II. Easter School in Agricultural Science (38th : 1983 :
University of Nottingham) [DNLM: 1. Mammals—Immunology—
Congresses. 2. Reproduction—Congresses. WQ 205 1322
1983]
QP251.14415 1984 599'.016 84-3097
Typeset by Scribe Design, Gillingham, Kent
Printed in England by Robert Hartnoll Ltd, Bodmin, Cornwall
PREFACE
The Thirty-Eighth University of Nottingham Easter School acted as a
forum for immunologists and reproductive physiologists, two groups of
scientists who are, increasingly, finding common areas of interest. This is
reflected in the fact that at the Easter School over one hundred delegates
from fifteen countries and with a wide range of interests attended
presentations from twenty-seven speakers.
The early part of the meeting was concerned with fundamental aspects of
immunology and reproductive immunology. Under the former heading
were considered the cellular basis of the immune response, the structure
and synthesis of immunoglobulins and functional aspects of antibodies.
Under the latter heading, the immunology of sperm in the male and female
reproductive tracts and of pregnancy and the post-partum period in a
variety of species were dealt with. The conference then moved on to
evaluate potential practical applications of immunological techniques to
the control of human population and the reproduction of domestic
animals. Thus there was a very full programme, the formal sessions
spanning all the major fields of investigation in the general area of
reproductive immunology.
I am aware that many useful contacts were made at the Easter School
and that information has been exchanged and research cooperation
instituted subsequently by delegates who met for the first time at Sutton
Bonington. While the chapters in this volume cannot reflect this benefit or
the value of informal discussions held both inside and outside the
conference hall, they provide the reader with the distilled experience of
authors who have worked for many years in their respective fields. I hope
that Immunological aspects of reproduction in mammals will constitute a
valuable reference text for those already involved in such work and a
stimulus for others to enter this complex and fascinating area of research.
D. B. Crighton
ν
ACKNOWLEDGEMENTS
It is a pleasure to acknowledge all those who presented papers and took
part in the discussions at the Easter School, thus contributing to a lively
and successful meeting.
I was delighted that Dr B.CL. Weedon, Vice-Chancellor of the
University of Nottingham was able to open the conference and welcome
the delegates. The subsequent smooth running of the formal sessions owed
much to the expert chairmanship of W.G. Reeves, G.A. Voisin, D.G.
Porter, R.E. Billingham, P.W. Wells, V.C. Stevens, H.M. Fraser and
G.R. Foxcroft.
The following organizations made donations to the expenses of speakers
from overseas and are acknowledged with gratitude:
The British Council
Glaxo Animal Health Limited
Hoechst AG
Hoechst UK Limited
Intervet International BV
Johnson & Johnson
Journals of Reproduction and Fertility Limited
The Wellcome Foundation Limited
Finally, I should like to thank those staff and postgraduate students from
Sutton Bonington who contributed in various ways to the success of the
meeting. My particular appreciation goes to Mrs Pamela Blythe who acted
as conference secretary.
D.B. Crighton
vii
1
THE CELLULAR BASIS OF THE IMMUNE RESPONSE
ELIZABETH SIMPSON
Medical Research Council, Clinical Research Centre, Harrow, Middlesex,
UK
The lymphoid system
The main function of the immune system is to make specific responses
against molecules identifiable as foreign. The possession of cells with
specific receptors and an ability to discriminate between self and non-self is
essential for this function.
The immune system consists of two cell types which possess specific
receptors, the Β cells and Τ cells, and of accessory cells such as
macrophages and dendritic cells which do not possess specific receptors but
which process and present antigens, i.e. the foreign determinants against
which the immune response is to be mounted. Β and Τ cells are
lymphocytes and they are present in the body, both in lymphoid organs
such as the thymus, lymph nodes and spleen, and in the circulation; in
blood they comprise the white blood cells. Accessory cells are also present
in the lymphoid organs and to a lesser extent in blood and lymph. There is
a constant traffic of lymphocytes between the lymphoid organs and the
blood and lymphatic circulation. Lymphocytes can leave blood capillaries,
passing through or between capillary endothelium. They migrate through
the tissues and can become involved in inflammatory processes, or migrate
into more sessile positions in lymph nodes, or be carried via the lymphatic
drainage channels which are present in all tissues. These eventually feed
into the principal lymphatic duct, the thoracic duct, which leads back into
the blood circulation. Such a roving population is thus suited ideally to
surveying all parts of the body for foreign invaders such as micro-organisms
and parasites.
All lymphoreticular cells, i.e. Τ and Β cells and accessory cells as well as
haemopoietic cells, arise from a common stem cell in the bone marrow.
The maturation pathway of each cell type is, however, very different {see
Golub, 1981). Τ cell precursors migrate from the bone marrow to the
thymus where they undergo a series of differentiation steps, including the
acquisition of cell surface markers which can be used to distinguish Τ cell
sub-populations in the periphery. Differentiated Τ cells migrate from the
thymus into the circulation and thence to the lymphoid organs, lymph
nodes and spleen. In these organs they may undergo further maturation.
1
2 Cellular basis of the immune response
Whilst the thymus is the well-identified organ in which Τ cells differentiate
from their bone marrow precursors, the comparable lymphoid organ for
the maturation of Β cells in mammals has not been identified
unequivocally, although in mammals it may be the rather diffuse
gut-associated lymphoid tissue. In birds, a discrete gut-associated
lymphoid organ, the Bursa of Fabricius, is clearly the place where Β cell
differentiation takes place. In addition to Β and Τ cells, monocytes are
present in the blood. These are not-fully-differentiated accessory cells,
which probably mature in situ in the lymph organs and all the other tissues
of the body in which they are found. Almost all organs and tissues contain
accessory cells, which probably do not migrate extensively, but can become
involved in inflammatory processes and present antigen wherever they are.
The major histocompatibility complex
In order to function as a system to protect the organism from foreign
invasion, a means of discrimination between what constitutes self and
distinguishes it from non-self, or foreign, is essential. The basis of this
ability to discriminate was, for many years, poorly understood, although
Burnet (1959) postulated that any clones of lymphocytes with receptors
capable of recognizing self determinants would be eliminated. Empirically,
Burnet was right, but paradoxically, the ability of Τ cells to recognize
foreign antigens has been found recently to be based on their ability to
recognize self major histocompatibility antigens. This is the phenomenon
of H-2 restriction, originally discovered for one functional sub-population
of Τ cells, the cytotoxic Τ cells (Tc), but it was subsequently found to be
true of all Τ cells.
In order to understand better the many roles of Τ cells in the immune
response, i.e. as effectors as well as modulators, it is necessary to
summarize our current knowledge of the major histocompatibility complex
(MHC) {see Klein, 1975, 1982).
Originally, the MHC was discovered because it controlled graft
rejection. Skin or tumour grafts between members of one inbred mouse
strain could be exchanged and would not be rejected but if such grafts were
exchanged between members of two different inbred mouse strains,
rejection took place. Genetic analysis of the loci which controlled the graft
rejection response showed that the most rapid graft rejection occurred
when donor and recipient possessed different alleles of a locus on
chromosome 17 called H-2. This was called the major histocompatibility
locus (now 'complex' because it consists of several linked loci). In contrast,
when the MHCs of donor and recipient were matched, differences at a
number of other loci were found to cause graft rejection, but at a much
slower rate. These loci were then called minor histocompatibility loci. The
MHC loci were defined by graft rejection and by serology since by
appropriate inter-strain immunization it was possible to raise antibodies to
the allelic forms of the loci of this complex. Immunogenetic analysis,
involving the use of intra-H-2 recombinant mouse strains, monoclonal
antibodies and gene cloning now enable us to draw a detailed map of the
H-2 region, as shown in Figure 1.1 {see also Melief, 1983).
Elizabeth Simpson 3
ΙΑ IE
subregion subregion
o - y/
Centromere Κ Aß Aa Eß Ea DL Qa Τ La
I region
Glycoprotein type I Π Π Π Π I I I 1
Figure 1.1 The mouse Η-2 complex on chromosome 17
The important distinctions to make are those between the class I and
class II genes of the MHC. Both gene classes code for glycoproteins which
are expressed on the cell surface (Figures 1.1 and 1.2), but their structures
are somewhat dissimilar and they subserve functions, which although
analogous, control different types of cell interaction of the immune system.
Class I MHC antigens consist of a heavy chain of molecular weight
45 000 D which has three external domains, N, CI and C2, a hydrophobic
transmembrane piece and an intracytoplasmic tail. Such heavy chains are
coded by the H-2K, D and L genes and also the Qa and Tla genes which lie
telomeric to H-2L. The other component of class I MHC antigens is a light
chain of 12 000 D. The structural gene for this is on chromosome 2 in the
mouse, and it is expressed as a single domain non-covalently linked with
the C2 domain of the class I heavy chain (Figure 1.2).
Class II MHC antigens are two-chain transmembrane structures. The α
chain is 33 000 D and the β chain is 28 000 D. Each chain consists of two
external domains, a hydrophobic transmembrane sequence and an
intracytoplasmic tail (Figure 1.2). The class II MHC genes are coded in the
v
H-2I region. Both th e a and β genes for the IA molecule are in the IA sub
region, and this region also contains the β gene for the IE molecule. The α
chain of the IE molecule lies in the IE subregion (Figure 1.1).
Class I MHC molecules, and to a slightly lesser extent, class II
molecules, are extraordinarily polymorphic. Polymorphic determinants are
Class I Class II
Figure 1.2 Major histocompatibility complex (MHC) molecules
4 Cellular basis of the immune response
associated with amino acid sequence differences in the N, CI and C2
domains of the class I heavy chains, and in the β chain of the class II
molecule. Allelic differences in both class I and class II MHC molecules
are recognized by both Τ and Β cells.
All mammalian species so far examined have an MHC and MHC
antigens of the class I and class II type described for the mouse. In the
human the MHC is the HLA complex, in the rat RT-1, in the dog DLA
and in the pig PLA.
Cellular and humoral immunity
There are two arms of the immune response, the cellular and the humoral.
Their control is tightly linked but they show certain distinctive features
which reflect the effector cell types mediating them. By humoral immunity
we mean antibody responses, the secreted immunoglobulins which are
carried through the body via the blood circulation and tissue fluids from
their site of manufacture by Β lymphocytes. By cellular immunity we mean
a group of responses such as graft rejection, delayed type hypersensitivity
and Tc responses, carried out or initiated by the various sub-populations of
Τ lymphocytes. Humoral and cellular immune responses are intercon-
nected in the senses that almost all Β cell responses require Τ cell help, and
that the presence of each type of response to determinants on the same
foreign antigen modifies the other. However, Β lymphocytes are different
from Τ lymphocytes with respect to their specific receptors and their
triggering requirements and within Τ lymphocytes there are several
functionally distinct sub-populations.
Both Β and Τ lymphocytes show the hallmark of specificity. They have
receptors for antigen and these are clonally distributed. Β cell receptors are
immunoglobulin, and when Β cells mature to antibody-producing cells
after antigen stimulation and help, they secrete immunoglobulin of the
same specificity as their membrane bound receptors. The antibody
response to most foreign antigens is dependent on Τ cell help. Β cells need
to be triggered to differentiate by two signals, one, the binding of antigen
by their receptors and the other a Τ helper cell signal usually delivered by
virtue of the Τ helper cell responding to another determinant (the 'carrier')
on the same molecule of antigen. This is the hapten-carrier effect of
Mitchison (1971).
The receptors on Τ cells are very poorly understood and Τ cells cannot
recognize foreign antigens and bind them directly, in the way that Β cells
can. Nevertheless Τ cells are very specific as exemplified by the ability of
delayed hypersensitivity responses (mediated by delayed type hypersensi-
tivity (Tdh) cells) to discriminate between small changes in the amino acid
sequence of synthetic polypeptides, by Τ helper cells (Th) to distinguish
between carrier determinants on hapten-modified molecules (Mitchison,
1971) and by Tc to distinguish between virus presented on target cells of
different MHC haplotype (Doherty, Blanden and Zinkernagel, 1976). This
last-mentioned observation and its interpretation have illuminated our
view of what Τ cells recognize, basically not foreign antigens per se, but
foreign antigens in the context of self MHC molecules, i.e. they are
Elizabeth Simpson 5
Table 1.1 MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) RESTRICTION OF
VIRUS-SPECIFIC Τ CELLS
Target cell destruction
BALB/c BALB/c C3H C3H
Virus immune mouse (H-2) uninfected infected uninfected infected
d d d
BALB/c (H-2K I D ) - + - -
C3H (H-2KkIkDk) — — — +
Infected target cells of responder type are lysed
MHC-restricted. This was shown originally for cytotoxic cells recognizing
viruses by Zinkernagel and Doherty (1974). The immunogen (virus) used
to generate the cytotoxic response was presented on cells syngeneic (=
genetically identical) with the responder, either in vivo or in vitro. After an
appropriate interval of five to seven days, the cytotoxic cells so generated
were assayed in vitro in a short-term Cr release assay using a panel of
target cells of various genotypes both uninfected and infected with the
immunizing virus. Syngeneic infected target cells were lysed, but not those
which were uninfected, showing the virus specificity of the response (Table
1.1). All target cells sharing MHC class I antigens with the responders were
also lysed providing they were virus-infected, but no MHC class I
non-identical virus-infected (or virus-uninfected) targets were lysed (Table
1.2). These findings showed that virus was recognized only in association
with self-MHC-class I molecules, i.e. the target antigen was not virus, but
virus plus self-MHC-antigen. The manner in which recognition of such an
entity is accomplished is still understood imperfectly. It has been proposed
either that the Τ cell has two receptors, one which recognizes self-MHC
and the other which recognizes the foreign determinant such as virus ('dual
recognition') or that it has a single receptor which recognizes a
conformational change in the self-MHC-molecule caused by the proximity
of the virus ('altered self) (for review see Matzinger, 1981). It has proved
difficult to design experiments to resolve this question but some form of
'altered self model is currently more favoured (Matzinger, 1981).
Experiments predating those of Zinkernagel and Doherty (1974) and
analysing Th responses showed that following immunization, helper cells
responded to antigen presented on cells genetically matched with those
present during immunization (Katz et al, 1973; Rosenthal and Shevach,
1973). These results are consistent with MHC restriction of helper cells and
this has subsequently been confirmed and extended (Erb and Feldmann,
1975; Schwartz et al., 1978). It is now clear that not only Tc and Th but Tdh
Table 1.2 MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) RESTRICTION OF
VIRUS SPECIFIC Τ CELLS
Target cell destruction of virus infected
cells from BIO congenic mouse strains
BIO B10.D2 B10.HT1 B10.HTG
Virus immune mouse (H-2KID) (bbb) (ddd) (bbd) (dab)
BlO(bbb) + + +
Infected target cells sharing class I MHC molecules are lysed
